Spiegel quoted NSA papers dating from February and labelled “top secret” and “not for foreigners” describing the agency’s success in spying on the so-called Sea-Me-We 4 undersea cable system.

The massive bundle of fibre optic cables originates near the southern French city of Marseille and links Europe with north Africa and the Gulf states, continuing through Pakistan and India to Malaysia and Thailand.

“Among the companies that hold ownership stakes in it are France Telecom, now known as Orange and still partly government-owned, and Telecom Italia Sparkle,” Spiegel said.

It said NSA specialists had hacked an internal website belonging to the operator consortium to mine documents about technical infrastructure including circuit mapping and network management information.

“More operations are planned in the future to collect more information about this and other cable systems,” Spiegel quoted the NSA documents as saying.

Der Spiegel has over the last several months reported on mass NSA spying on targets in the United States and abroad using documents provided by fugitive intelligence contractor Edward Snowden.

A White House-picked panel this month recommended curbing the secretive powers of the NSA, warning that its spying sweeps in the “war on terror” had gone too far.